Currently, standardization of a 4G radio communication system is under progress by 3GPP (Third Generation Partnership Project). According to the 4G, an improvement in maximum communication speed and a quality improvement in cell edges can be realized by using technologies such as relays and carrier aggregation. Further, considerations are given to improving coverage by introducing base stations other than eNodeB (macro-cell base station), such as NeNB (Home eNodeB, femtocell base station, compact base station for cell phones) and RRH (Remote Radio Head).
(Paging)
Further, in the LTE, an RRC_Connected mode and an RRC_Idle mode are defined. The RRC_Connected mode is a state in which a connection is established between the UE and the eNodeB, and the UE is capable of sending an uplink signal and receiving a downlink signal. On the other hand, the RRC_Idle mode is a state in which power of the UE is saved, and the UE in the RRC_Idle mode monitors the paging channel from the eNodeB, and transitions to the RRC_Connected mode when being called in the paging channel.
Here, for example, if the UE is called, since the eNodeB sends the paging channel at a timing that arrives in a cycle called a paging cycle, the UE of the RRC_Idle mode monitors the paging channel at the paging cycle. Although power consumption of the UE can be reduced when the paging cycle is long, there is a tendency that a delay from when the UE is called to when it responds becomes large. Notably, an intermittent receiving cycle that is similar to this is disclosed for example in Patent Literature 1.
(MTC)
On the other hand, debates on MTC (Machine Type Communications) are also in progress in the 3GPP. The MTC is generally synonymous to M2M (Machine to Machine), and refers to a communication between machines and not directly used by a human. The MTC primarily is performed between a server and a MTC terminal that is not directly used by a human.
For example, as a medical application of the MTC, a case may be assumed in which an MTC terminal collects electrocardiogram information of a human, and transmits the electrocardiogram information to a server by using uplink when a certain trigger condition is met. As another application of the MTC, a case may be assumed in which a vending machine is caused to function as an MTC terminal, and a server causes the vending machine under management to report sales once every certain cycle (for example, every 30 days).
Such an MTC terminal by way of example has the following features in general, however, not every MTC terminal needs to have all of the following features, and which of the features is to be endowed depends on applications.
Scarce needs to move (Low Mobility)
Transmission of small data (Online Small Data Transmission)
Very low power consumption (Extra Low Power Consumption)
Handled by grouping respective MTCs (Group-based MTC Features)